The present invention relates to disposable hygiene products and more specifically, to methods and apparatuses for processing disposable hygiene products such as baby diapers, adult diapers, disposable undergarments, incontinence devices, sanitary napkins and the like.
More specifically, the invention relates to a novel vacuum commutation system to pucks or other structures. Vacuum is used in many parts of a diaper manufacturing process. For instance, during pulp core formation, vacuum draws pulp fibers into forming pockets on a core forming drum. Elsewhere along the manufacturing process, vacuum is used. For instance, a common method of applying discrete pieces of one web to another is by use of a slip-and-cut applicator. A slip-and-cut applicator is typically comprised of a cylindrical rotating vacuum anvil, a rotating knife roll, and a transfer device. In typical applications, an incoming web is fed at a relatively low speed along the vacuum face of the rotating anvil, which is moving at a relatively higher surface speed and upon which the incoming web is allowed to “slip”. A knife-edge, mounted on the rotating knife roll, cuts a off a segment of the incoming web against the anvil face. This knife-edge is preferably moving at a surface velocity similar to that of the anvil's surface. Once cut, the web segment is held by vacuum drawn through holes on the anvil's face as it is carried at the anvil's speed downstream to the transfer point where the web segment is transferred to the traveling web. Vacuum can also be used in vacuum conveyors.
Some components of disposable products such as ears, or extension panels, require transportation and deposition by a vacuum puck. For instance, in U.S. Pat. No. 8,016,972, assigned to the same assignee as the present invention, ear webs are severed into individual ears, and rotated while held by a vacuum puck, to be applied to a traveling web such as a chassis web.
An ear is a component of a diaper that is grasped and pulled around the waist of a wearer. Typically, ears are secured to the diaper at a first end, and a second free end is typically equipped with securing means, such as a pressure sensitive adhesive, or hook and loop material. As a user grasps an ear and pulls the ear, elasticity provided about the waist region of the diaper allows the free end to be snugly pulled about the waist of a wearer, and coupled to the diaper. Ears can be rectangular or made of irregular shapes.
Typical vacuum pucks used in the prior art have rows of vacuum holes which are fed by cross-drilled ports, each being exposed to the source of vacuum by commutations, as the ports move into a zone of negative pressure in a stationary manifold. Such a configuration serves to apply vacuum sequentially and piecewise (vacuum application is discretized) to each successive row of holes. Such a configuration is shown in U.S. Pat. No. 7,533,709, incorporated herein by reference. At high speeds, it has been found that air entering the vacuum ports is drawn across an article carrying face of the puck, and the air drawn into the ports can adversely impact control over the discrete components by causing misalignment, folding or other loss of total control.
Continual improvements and competitive pressures have incrementally increased the operational speeds of disposable diaper converters. As speeds increased, the mechanical integrity and operational capabilities of the applicators had to be improved accordingly. The prior art is quite successful when processing full-width or symmetrical webs using vacuum, and vacuum is nearly universally used in diaper production. However, as speeds have increased in manufacturing, so too has vacuum demand. Along with significant increase in vacuum demand comes the expense of powering convention vacuum forming techniques, and the noise associated with traditional vacuum pumps.
The disclosed invention provides an apparatus which can provide a better solution for tightly controlled zones of vacuum commutation. The vacuum can be used for whatever purpose desired, including maintaining control over diaper webs or discrete portions of diaper webs, including sections of various shapes, and to decrease reliance on traditional vacuum generation.